The Pulsation Mode and Distance of the Cepheid FF Aquilae

The determination of pulsation mode and distance for field Cepheids is a complicated problem best resolved by a luminosity estimate. For illustration a technique based on spectroscopic luminosity discrimination is applied to the 4.47d s-Cepheid FF Aql. Line ratios in high dispersion spectra of the variable yield values of =-3.40+-0.02 s.e.(+-0.04 s.d.), average effective temperature Teff=6195+-24 K, and intrinsic color (-)o = +0.506+-0.007, corresponding to a reddening of E(B-V)=0.25+-0.01, or E(B-V)(B0)=0.26+-0.01. The skewed light curve, intrinsic color, and luminosity of FF Aql are consistent with fundamental mode pulsation for a small amplitude classical Cepheid on the blue side of the instability strip, not a sinusoidal pulsator. A distance of 413+-14 pc is estimated from the Cepheid's angular diameter in conjunction with a mean radius of =39.0+-0.7 Rsun inferred from its luminosity and effective temperature. The dust extinction towards FF Aql is described by a ratio of total-to-selective extinction of Rv=Av/E(B-V)=3.16+-0.34 according to the star's apparent distance modulus.Comment: To appear in ApJ

Heuristic Models of Two-Fermion Relativistic Systems with Field-Type Interaction

We use the chain of simple heuristic expedients to obtain perturbative and exactly solvable relativistic spectra for a family of two-fermionic bound systems with Coulomb-like interaction. In the case of electromagnetic interaction the spectrum coincides up to the second order in a coupling constant with that following from the quantum electrodynamics. Discrepancy occurs only for S-states which is the well-known difficulty in the bound-state problem. The confinement interaction is considered too. PACS number(s): 03.65.Pm, 03.65.Ge, 12.39.PnComment: 16 pages, LaTeX 2.0

Haploid biotechnology as a tool for creating a selection material for sugar beets

Since the discovery of the phenomenon of haploidy, biotechnology has become an integral part in the successful creation of new varieties and hybrids of various plant species. In particular, these technologies are actively used in agriculture, which is concerned with increasing the volume and improving the quality of products. The integration of haploid production techniques together with other available biotechnological tools such as marker selection (MAS), induced mutagenesis and genetic engineering technologies can significantly accelerate crop breeding. This article shows the main stages in the development of biotechnology since 1921. Now they are successfully used to create doubled haploids to accelerate the selection process of various plants and, in particular, sugar beet, which is the most important sugar crop in regions with a temperate climate. There are several methods for obtaining forms with a single set of chromosomes. For sugar beets, the use of gynogenesis turned out to be expedient, since in this case the other methods turned out to be ineffective in the mass production of haploids. The article considers the stages of obtaining the H and DH lines of Beta vulgaris L., as well as the main stages of biotechnological production of homozygous breeding material of this culture. These stages include selecting parental forms – donor explants, sterilizing buds and introducing non-pollinated ovules in vitro, obtaining haploids, doubling their chromosome set, creating doubled haploids, determining ploidy at different stages, relocating the obtained plants to greenhouses and growing stecklings. A number of advantages that the technology of creating doubled haploids in vitro has in comparison with traditional methods of selection are described. It has been shown that the use of these approaches is relevant when obtaining new highly productive hybrids and varieties of agricultural plants; however, the methods for the production of homozygous forms in sugar beet still require additional research aimed at increasing the efficiency and reproducibility of each stage of the process

Reddenings of FGK supergiants and classical Cepheids from spectroscopic data

Accurate and homogeneous atmospheric parameters (Teff, log (g), Vt, [Fe/H]) are derived for 74 FGK non-variable supergiants from high-resolution, high signal-to-noise ratio, echelle spectra. Extremely high precision for the inferred effective temperatures (10-40 K) is achieved by using the line-depth ratio method. The new data are combined with atmospheric values for 164 classical Cepheids, observed at 675 different pulsation phases, taken from our previously published studies. The derived values are correlated with unreddened B-V colours compiled from the literature for the investigated stars in order to obtain an empirical relationship of the form: (B-V)o = 57.984 - 10.3587(log Teff)^2 + 1.67572(log Teff)^3 - 3.356(log (g)) + 0.0321(Vt) + 0.2615[Fe/H] + 0.8833((log (g))(log Teff)). The expression is used to estimate colour excesses E(B-V) for individual supergiants and classical Cepheids, with a precision of +-0.05 mag. for supergiants and Cepheids with n=1-2 spectra, reaching +-0.025 mag. for Cepheids with n>2 spectra, matching uncertainties for the most sophisticated photometric techniques. The reddening scale is also a close match to the system of space reddenings for Cepheids. The application range is for spectral types F0--K0 and luminosity classes I and II.Comment: accepted for publication (MNRAS

Hadron production in lepton-nuclei interactions at high energies: Monte Carlo generator HARDPING 2.0

Hadron production in lepton-nucleus interactions at high-energies is considered in framework of developing Monte Carlo event generator HARDPING (HARD Probe INteraction Generator). Such effects as formation length, energy loss and multiple rescattering for produced hadrons and their constituents are implemented into the HARDPING 2.0. Available data from HERMES collaboration on hadron production in lepton-nucleus collisions are described by the present version of the HARDPING generator in a reasonable agreement.Comment: 7 pages, 3 figure

Optical Multicolor WBVR-Observations of the X-Ray Star V1341 Cyg = Cyg X-2 in 1986-1992

We present the results of $WBVR$ observations of the low-mass X-ray binary V1341 $\textrm{Cyg} = \textrm{Cyg}$ X--2. Our observations include a total of 2375 individual measurements in four bands on 478 nights in 1986-1992. We tied the comparison and check stars used for the binary to the $WBVR$ catalog using their $JHK$ magnitudes. The uncertainty of this procedure was 3$$ in the $B$ and $V$ bands and 8%-10% for the $W$ and $R$ bands. In quiescence, the amplitude of the periodic component in the binary's $B$ brightness variations is within $0.265^{m}{-}0.278^{m}$ ($0.290^{m}{-}0.320^{m}$ in $W$); this is due to the ellipsoidal shape of the optical component, which is distorted with gravitational forces from the X-ray component. Some of the system's active states (long flares) may be due to instabilities in the accretion disk, and possibly to instabilities of gas flows and other accretion structures. The binary possesses a low-luminosity accretion disk. The light curves reveal no indications of an eclipse near the phases of the upper and lower conjunctions in quiescence or in active states during the observed intervals. We conclude that the optical star in the close binary V1341 $\textrm{Cyg} = \textrm{Cyg}$ X-2 is a red giant rather than a blue straggler. We studied the long-term variability of the binary during the seven years covered by our observations. The optical observations presented in this study are compared to X-ray data from the Ginga observatory for the same time intervals.Comment: 35 pages, 8 figure